Growth of nanostructures by cluster deposition: Experiments and simple models

This paper presents simple models useful in analyzing the growth of nanostructures obtained by cluster deposition. After a brief survey of applications and experimental methods, the author describes the Monte Carlo techniques for simulating nanostructure growth. Simulations of the first stages, the submonolayer regime, are reported for a wide variety of experimental situations: complete condensation, growth with reevaporation, nucleation on defects, and total or null cluster-cluster coalescence. [Note: Software for all these simulation programs, which are also useful for analyzing growth from atomic beams, is available on request from the author.] The aim of the paper is to help experimentalists, in analyzing their data, to determine which processes are important and to quantify them. Experiments on growth from cluster beams are discussed, as is the measurement of cluster mobility on the surface. Surprisingly high mobility values are found. An important issue for future technological applications of cluster deposition is the relation between the size of the incident clusters and the size of the islands obtained on the substrate, which is described by an approximate formula depending on the melting temperature of the deposited material. Finally, the author examines the atomic mechanisms that can explain the diffusion of clusters on a substrate and their mutual interaction, to aggregate keeping their integrity or to coalesce.